The closest known prior art is U.S. Pat. No. 3,904,462 to Dimigen et al. This patent utilizes a mask of titanium or aluminum oxide to produce an etched structure having an inclined etch profile. The etching may be carried out to depths of one micrometer and more by adjusting one of the layer thickness of the mask and the angle of incidence of the ion beam so as to etch to the desired depth. However it is noted that the angle of etching conforms exactly to the angle of taper of the mask and the mask is of a material substantially immune to ion etching or removal. The problem is thus transferred to production of a dimensionally accurate mask with repeatably sloped walls. This requires several processing steps in addition to the standad lithography and etching procedures.